The proposed research is to elucidate the nature of aging in reproductive tissues. This approach will involve studies of gonadotropic hormone effects on ovarian cell suspensions in culture in terms of steroid hormone secretion and the changes in adenylate cyclase system. The types and amount of steroid hormone produced in vitro will be measured by radioimmunoassay. The gonadotropic hormone receptor present in the ovarian cell suspension culture from growing and dying ovaries will be measured by their ability to bind iodinated hormone. Adenylate cyclase activity and cyclic AMP phosphodiesterase will be measured by their ability to convert ATP to cyclic AMP and the destruction of cyclic AMP respectively; the amount of the cyclic AMP in the culture system will be measured by a protein binding assay. Finally the heterogenous cell suspensions will be separated by density gradient centrifugation into subpopulations of cell types. The effect of various gonadotropins on the different cell types will be investigated. The findings will serve as a key toward the understanding of how gonadotropic hormones are involved in growing and aging tissue in culture.